Robust H-infinite loop shaping controller based on hybrid PSO and harmonic search for frequency regulation in hybrid distributed generation system

This paper presents a study on frequency regulation in isolated hybrid distributed generation (DG) system. The hybrid DG system consists of wind turbine generator (WTG), photovoltaic (PV), aqua-electrolyzer (AE), fuel cell (FC) and diesel engine generator (DEG) along with storage like flywheel energy storage system (FESS), battery energy storage system (BESS) and ultra-capacitor (UC). H-infinite loop shaping based on particle swarm optimization (PSO) as well as hybrid particle swarm optimization and harmonic search (PSOHS) controller is proposed to minimize the frequency deviation. The controller performance is analyzed under wide-band range of wind speed based on Van-der Hoven model, random load demand and non-linear solar-radiation variation which are considered as disturbances into the system. Also, the controller robustness is tested for changes in parameter up to - 30% of its nominal value. The simulated results under different operating scenarios demonstrate minimum frequency deviation in hybrid system, being achieved by the proposed controllers with use of UC as storage combination along with FESS in comparison to a simple PSO tuned PID controller. (C) 2014 Elsevier Ltd. All rights reserved.